Flex/actionscript 中 F5 和浏览器关闭事件的区别

我使用下面的代码来确定浏览器窗口的关闭，它工作得很好。但是，当用户使用“F5”或单击浏览器刷新按钮刷新页面时，就会出现问题，即使在这种情况下也会调用同一段代码。

我想知道是否有什么办法可以使用动作脚本区分浏览器关闭事件和刷新事件

package utils
{
import flash.external.ExternalInterface;

public class ExternalInterfaceUtil
{
    public static function addExternalEventListener( qualifiedEventName:String, callback:Function,callBackAlias:String ):void
    {
        // 1. Expose the callback function via the callBackAlias
        ExternalInterface.addCallback( callBackAlias, callback );
        // 2. Build javascript to execute
        var     jsExecuteCallBack:String = "document.getElementsByName('"+ExternalInterface.objectID+"')[0]."+callBackAlias+"()";
        var jsBindEvent:String = "function(){"+qualifiedEventName+"= function(){"+jsExecuteCallBack+"};}";
        // 3. Execute the composed javascript to perform the binding of the external event to the specified callBack function
        ExternalInterface.call( jsBindEvent );
    }
}
}

对上述实用程序的调用是通过

ExternalInterfaceUtil.addExternalEventListener("window.onunload",handleLogout,"unloadFlex");

伪代码：

public static function addExternalEventListener( qualifiedEventName:String, callback:Function,callBackAlias:String ):void
{
   if(lastKeyPressed.KeyCode != 116)
   {
    // 1. Expose the callback function via the callBackAlias
    ExternalInterface.addCallback( callBackAlias, callback );
    // 2. Build javascript to execute
    var     jsExecuteCallBack:String = "document.getElementsByName('"+ExternalInterface.objectID+"')[0]."+callBackAlias+"()";
    var jsBindEvent:String = "function(){"+qualifiedEventName+"= function(){"+jsExecuteCallBack+"};}";
    // 3. Execute the composed javascript to perform the binding of the external event to the specified callBack function
    ExternalInterface.call( jsBindEvent );
 }
}